A method of this type is known from German Pat. No. 2,002,100. It shows a hydraulically driven sausage-filling and -twisting machine whose hydraulic motor is controlled by a rotary servovalve. The servovalve is set stepwise by a servomotor and the hydraulic motor follows the predetermined control displacement. Since the rotation angle of the hydraulic motor is proportional to the volume of the discharged mass very good accuracy is obtained. As a result of the displacement following procedure this arrangement can only be used with a hydraulic drive and with relatively great expense for the controls.
In any situation where the portioning operation is initiated and ended by control commands the volumetric accuracy of the filling operation is largely determined by the overrun, that is the amount discharged between the shutoff command and the complete stopping of the portioning element. The size of this overrun mass is dependent on several factors, but mainly on the stepping speed or filling speed, and also on the type and makeup of the drive, the working temperature, the cleanliness of the equipment, wear of the drive parts and the like. Above all when the dosing is carried out by measuring the time between the switch-on and switch-off command, it is necessary periodically to carry out monitoring measurement and to correct the setting if adequate portioning accuracy is to be obtained. Even so, the set control value remains constant for a certain time. If in the meanwhile the operating conditions change, the thus created deviations in the filling operation remain until the next monitoring and changing of the control value.